Malnutrition as an enteric infectious disease with long-term effects on child development

Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil

OBJECTIVE

Apolipoprotein E4 may benefit children during early periods of life when the body is challenged by infection and nutritional decline. We examined whether apolipoprotein E4 affects intestinal barrier function, improving short-term growth and long-term cognitive outcomes in Brazilian shantytown children.

METHODS

A total of 213 Brazilian shantytown children with below-median height-for-age z-scores (HAZ) received 200,000 IU of retinol (every four months), zinc (40 mg twice weekly), or both for one year, with half of each group receiving glutamine supplementation for 10 days. Height-for-age z-scores, weight-for-age z-scores, weight-for-height z-scores, and lactulose:mannitol ratios were assessed during the initial four months of treatment. An average of four years (range 1.4-6.6) later, the children underwent cognitive testing to evaluate non-verbal intelligence, coding, verbal fluency, verbal learning, and delayed verbal learning. Apolipoprotein E4 carriage was determined by PCR analysis for 144 children.

RESULTS

Thirty-seven children were apolipoprotein E4(+), with an allele frequency of 13.9%. Significant associations were found for vitamin A and glutamine with intestinal barrier function. Apolipoprotein E4(+) children receiving glutamine presented significant positive Pearson correlations between the change in height-for-age z-scores over four months and delayed verbal learning, along with correlated changes over the same period in weight-for-age z-scores and weight-for-height z-scores associated with non-verbal intelligence quotients. There was a significant correlation between vitamin A supplementation of apolipoprotein E4(+) children and improved delta lactulose/mannitol. Apolipoprotein E4(-) children, regardless of intervention, exhibited negative Pearson correlations between the change in lactulose-to-mannitol ratio over four months and verbal learning and non-verbal intelligence.

CONCLUSIONS

During development, apolipoprotein E4 may function concomitantly with gut-tropic nutrients to benefit immediate nutritional status, which can translate into better long-term cognitive outcomes.

Evidence for genetic susceptibility to developing early childhood diarrhea among shantytown children living in northeastern Brazil

To explore the genetic components of susceptibility to early childhood diarrhea (ECD), we used a quantitative genetic approach to estimate the heritability of ECD among children from two Brazilian favelas. Shared environment was used to model common exposure to environmental factors. Genetic relatedness was determined from pedigree information collected by screening household participants (n = 3,267) from two geographically related favelas located in Fortaleza, Brazil. There were 277 children within these pedigrees for whom diarrheal episodes in the first two years of life were recorded. Data on environmental exposure and pedigree relationship were combined to quantitatively partition phenotypic variance in ECD into environmental and genetic components by using a variance components approach as implemented in Sequential Oligogenic Linkage Analysis Routines program. Heritability accounted for 54% of variance in ECD and proximity of residence effect accounted for 21% (P < 0.0001). These findings suggest a substantial genetic component to ECD susceptibility and the potential importance of future genetics studies.

Developing novel antisecretory drugs to treat infectious diarrhea

Diarrhea, a disease of poverty and poor sanitation, kills an estimated two million children each year. Oral rehydration therapy is a very simple and inexpensive treatment that has significantly reduced mortality from secretory diarrhea caused by rotavirus, cholera and enterotoxigenic Escherichia coli. The efficacy and adoption of oral rehydration therapy would be enhanced by a drug that reduces fluid loss associated with these diseases and alleviates disease symptoms. Secretion and absorption by the intestine offer a number of potential drug targets to reduce fluid loss. Among these, the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is the most attractive because it is the primary driver of secretion in cases of diarrhea caused by enterotoxigenic bacteria. CFTR can be inhibited by both natural products and synthetic small molecules. iOWH032 is a synthetic CFTR inhibitor that has recently entered clinical trials for this indication.

Poor folate status predicts persistent diarrhea in 6- to 30-month-old north Indian children

Poor micronutrient status is associated with diarrheal illness, but it is not known whether low folate and/or cobalamin status are independent risk factors for diarrhea. We measured the association between plasma folate and cobalamin and subsequent diarrheal morbidity in a prospective cohort study of 2296 children aged 6-30 mo in New Delhi, India. Plasma concentrations of folate, cobalamin, total homocysteine (tHcy), and methylmalonic acid were determined at baseline. Whether a child had diarrhea was recorded during weekly visits in a 4-mo zinc supplementation trial. Diarrhea episodes lasting <7, ≥7, and ≥14 d were classified as acute, prolonged, and persistent, respectively. There was a total of 4596 child periods with acute, 633 with prolonged, and 117 with persistent diarrhea during follow-up. Children with plasma folate concentrations in the lowest quartile had higher odds of persistent diarrhea than children in the other quartiles [adjusted OR = 1.77 (95% CI = 1.14, 2.75); P = 0.01]. This effect differed between boys [adjusted OR = 2.51 (95% CI = 1.47, 4.28)] and girls [adjusted OR = 1.03 (95% CI = 0.53, 2.01); P-interaction = 0.030]. We found a small but significant association between high plasma tHcy concentration and acute diarrhea [adjusted OR = 1.14 (95% CI = 1.04, 1.24); P = 0.006]. Plasma cobalamin concentration was not a predictor of diarrheal morbidity. In conclusion, poor folate status was an independent predictor of persistent diarrhea in this population.

Challenges in understanding the immunopathogenesis of Cryptosporidium infections in humans

Water and foodborne enteric cryptosporidiosis is a globally emerging public health issue. Although the clinical manifestations of enteric cryptosporidiosis are generally limited to intestinal infection and subsequent diarrhoea, extra-intestinal invasion has also been diagnosed in immunocompromised individuals, particularly in those infected with human immunodeficiency virus (HIV) or AIDS. Due to an inadequate understanding of Cryptosporidium immunopathogenesis in humans, the development of vaccines or therapeutic agents and their application in diseases management is difficult. Current therapeutic measures are not fully effective in the treatment of the disease. Therefore, the implementation of strategies designed to control the chain of cryptosporidiosis transmission (environment ↔ human ↔ food/water ↔ animal) is a critical but challenging issue to public health authorities across the world. Several excellent studies have been done on innate, acquired and mucosal immunity against Cryptosporidium infections using animal models, in vitro human cell lines and human volunteers. However, there are still multiple challenges in understanding the intestinal immune response (immunopathogenesis) to Cryptosporidium infection in humans. This paper reviews recent updates on immunopathogenesis and immune responses to Cryptosporidium infection in humans, while also discussing the current limitations that exist regarding a precise understanding of the immunopathological mechanisms.

Alanyl-glutamine promotes intestinal epithelial cell homeostasis in vitro and in a murine model of weanling undernutrition

Alanyl-glutamine (Ala-Gln) has recently been shown to enhance catch-up growth and gut integrity in undernourished children from Northeast Brazil. We hypothesized that the intestinal epithelial effects of Ala-Gln in malnourished weanling mice and mouse small intestinal epithelial (MSIE) cells would include modulation of barrier function, proliferation, and apoptosis. Dams of 10-day-old suckling C57BL/6 pups were randomized to a standard diet or an isocaloric Northeast Brazil "regional basic diet," moderately deficient in protein, fat, and minerals. Upon weaning to their dam's diet on day of life 21, pups were randomized to Ala-Gln solution or water. At 6 wk of age, mice were killed, and jejunal tissue was collected for morphology, immunohistochemistry, and Ussing chamber analysis of transmucosal resistance and permeability. Proliferation of MSIE cells in the presence or absence of Ala-Gln was measured by MTS and bromodeoxyuridine assays. MSIE apoptosis was assessed by annexin and 7-amino-actinomycin D staining. Pups of regional basic diet-fed dams exhibited failure to thrive. Jejunal specimens from undernourished weanlings showed decreased villous height and crypt depth, decreased transmucosal resistance, increased permeability to FITC-dextran, increased claudin-3 expression, and decreased epithelial proliferation and increased epithelial apoptosis (as measured by bromodeoxyuridine and cleaved caspase-3 staining, respectively). Undernourished weanlings supplemented with Ala-Gln showed improvements in weight velocity, villous height, crypt depth, transmucosal resistance, and epithelial proliferation/apoptosis compared with unsupplemented controls. Similarly, Ala-Gln increased proliferation and reduced apoptosis in MSIE cells. In summary, Ala-Gln promotes intestinal epithelial homeostasis in a mouse model of malnutrition-associated enteropathy, mimicking key features of the human disease.

Stature and robusticity during the agricultural transition: evidence from the bioarchaeological record

The population explosion that followed the Neolithic revolution was initially explained by improved health experiences for agriculturalists. However, empirical studies of societies shifting subsistence from foraging to primary food production have found evidence for deteriorating health from an increase in infectious and dental disease and a rise in nutritional deficiencies. In Paleopathology at the Origins of Agriculture (Cohen and Armelagos, 1984), this trend towards declining health was observed for 19 of 21 societies undergoing the agricultural transformation. The counterintuitive increase in nutritional diseases resulted from seasonal hunger, reliance on single crops deficient in essential nutrients, crop blights, social inequalities, and trade. In this study, we examined the evidence of stature reduction in studies since 1984 to evaluate if the trend towards decreased health after agricultural transitions remains. The trend towards a decrease in adult height and a general reduction of overall health during times of subsistence change remains valid, with the majority of studies finding stature to decline as the reliance on agriculture increased. The impact of agriculture, accompanied by increasing population density and a rise in infectious disease, was observed to decrease stature in populations from across the entire globe and regardless of the temporal period during which agriculture was adopted, including Europe, Africa, the Middle East, Asia, South America, and North America.

Human nutrition, the gut microbiome and the immune system

Marked changes in socio-economic status, cultural traditions, population growth and agriculture are affecting diets worldwide. Understanding how our diet and nutritional status influence the composition and dynamic operations of our gut microbial communities, and the innate and adaptive arms of our immune system, represents an area of scientific need, opportunity and challenge. The insights gleaned should help to address several pressing global health problems.

Impacts of domestic violence on child growth and nutrition: a conceptual review of the pathways of influence

Domestic violence against women is a global problem, and young children are disproportionate witnesses. Children's exposure to domestic violence (CEDV) predicts poorer health and development, but its effects on nutrition and growth are understudied. We propose a conceptual framework for the pathways by which domestic violence against mothers may impair child growth and nutrition, prenatally and during the first 36 months of life. We synthesize literatures from multiple disciplines and critically review the evidence for each pathway. Our review exposes gaps in knowledge and opportunities for research. The framework also identifies interim strategies to mitigate the effects of CEDV on child growth and nutrition. Given the global burden of child malnutrition and its long-term effects on human-capital formation, improving child growth and nutrition may be another reason to prevent domestic violence and its cascading after-effects.

Malnutrition and gastrointestinal and respiratory infections in children: a public health problem

Infectious disease is the major cause of morbidity and mortality in developing countries, particularly in children. Increasing evidence suggests that protein-calorie malnutrition is the underlying reason for the increased susceptibility to infections observed in these areas. Moreover, certain infectious diseases also cause malnutrition, which can result in a vicious cycle. Malnutrition and bacterial gastrointestinal and respiratory infections represent a serious public health problem. The increased incidence and severity of infections in malnourished children is largely due to the deterioration of immune function; limited production and/or diminished functional capacity of all cellular components of the immune system have been reported in malnutrition. In this review, we analyze the cyclical relationship between malnutrition, immune response dysfunction, increased susceptibility to infectious disease, and metabolic responses that further alter nutritional status. The consequences of malnutrition are diverse and included: increased susceptibility to infection, impaired child development, increased mortality rate and individuals who come to function in suboptimal ways.

Acute phase reactants in Sudanese children with severe protein-energy malnutrition

The pre-dietary rehabilitation levels of acute phase proteins (APP) namely, alpha-1-antitrypsin (AAT), orosomucoid (ORO), haptoglobin (HAP), fibrinogen (FIB) and C-reactive protein (CRP) in the plasma of Sudanese children with severe protein energy malnutrition (PEM) were compared with those of normal controls, and with the levels after dietary rehabilitation. Eighty one children were included in the study; 49 with severe PEM (23 with marasmus, 17 with marasmic-kwashiorkor and 9 with kwashiorkor), 13 with tuberculosis (TB) and 19 healthy children as controls. The study showed a high incidence of infections, especially acute respiratory infection (ARI), diarrhoeal diseases and intestinal parasites in the malnourished children. The mean plasma level of albumin was significantly lower in the malnourished children compared to controls (P<0.001), with kwashiorkor children showing the lowest mean level. This hypoalbuminaemia was significantly associated with the presence of ARI and intestinal parasites. The mean plasma levels of the APP, except FIB, were significantly higher in malnourished children than in controls, with higher levels associated with ARI and the presence of fever. Malnourished children with TB had significantly higher mean levels of the APP (AAT, HAP, FIB, CRP) compared to those without TB. The mean levels of HAP and AAT were significantly lower in the presence of diarrhoea, suggesting their loss in the stool. The mean levels of the APP after two weeks dietary rehabilitation and antimicrobial treatment showed a significant drop in only two of the APP, namely CRP, ORO, while FIB showed a significant rise.

ApoE polymorphisms and diarrheal outcomes in Brazilian shanty town children

A series of studies have shown that the heavy burdens of diarrheal diseases in the first 2 formative years of life in children living in urban shanty towns have negative effects on physical and cognitive development lasting into later childhood. We have shown that APOE4 is relatively common in shanty town children living in Brazil (13.4%) and suggest that APOE4 has a protective role in cognitive development as well as weight-for-height in children with heavy burdens of diarrhea in early childhood (64/123; 52%), despite being a marker for cognitive decline with Alzheimer's and cardiovascular diseases later in life. APOE2 frequency was higher among children with heaviest diarrhea burdens during the first 2 years of life, as detected by PCR using the restriction fragment length polymorphism method, raising the possibility that ApoE-cholesterol balance might be critical for growth and cognitive development under the stress of heavy diarrhea burdens and when an enriched fat diet is insufficient. These findings provide a potential explanation for the survival advantage in evolution of genes, which might raise cholesterol levels during heavy stress of diarrhea burdens and malnutrition early in life.

Pediatric diarrhea in southern Ghana: etiology and association with intestinal inflammation and malnutrition

Diarrhea is a major public health problem that affects the development of children. Anthropometric data were collected from 274 children with (N = 170) and without (N = 104) diarrhea. Stool specimens were analyzed by conventional culture, polymerase chain reaction for enteroaggregative Escherichia coli (EAEC), Shigella, Cryptosporidium, Entamoeba, and Giardia species, and by enzyme-linked immunosorbent assay for fecal lactoferrin levels. About 50% of the study population was mildly to severely malnourished. Fecal lactoferrin levels were higher in children with diarrhea (P = 0.019). Children who had EAEC infection, with or without diarrhea, had high mean lactoferrin levels regardless of nutritional status. The EAEC and Cryptosporidium were associated with diarrhea (P = 0.048 and 0.011, respectively), and malnourished children who had diarrhea were often co-infected with both Cryptosporidium and EAEC. In conclusion, the use of DNA-biomarkers revealed that EAEC and Cryptosporidium were common intestinal pathogens in Accra, and that elevated lactoferrin was associated with diarrhea in this group of children.

Campylobacter jejuni and Campylobacter coli in children from communities in Northeastern Brazil: molecular detection and relation to nutritional status

This study determined the prevalence of Campylobacter jejuni/coli and its relation with nutritional status in children from Northeastern Brazil. This was a case-control study design. Stool samples were evaluated for hipO (C. jejuni), ask (C. coli), and cdtABC (C. jejuni's cytolethal distending toxin) genes. The nutritional status from these children was assessed by anthropometric measures and z-scores. C. jejuni and C. coli were detected in 9.6% (8/83) and 6.0% (5/83) in the diarrhea group and in 7.2% (6/83) and 1.2% (1/83) of the nondiarrhea group, respectively. Children with positive molecular detection of C. jejuni showed significantly lower z-scores than children without C. jejuni. The cdtABC operon was found in 57% of hipO(+) samples. C. jejuni/coli prevalence was similar in diarrhea and nondiarrhea groups. There was a significant association of C. jejuni infection with lower nutritional status.

Vaccines for all: Institut Pasteur vaccinology course, 2010

A comprehensive 5-week vaccinology course was recently held in Paris (1 March-2 April 2010) hosted by the Institut Pasteur, a world-renowned center for science and vaccinology. A total of 25 young scientists from different parts of the world participated and 63 world experts gave lectures in six specific modules that covered all aspects of vaccinology, from basic research to clinical studies. Students also had the opportunity to attend a 2-day "Pandemic Influenza Workshop". This article summarizes the issues discussed during this course and highlights the importance of global access to vaccines.

Use of metagenomics to understand the genetic basis of malnutrition

Childhood malnutrition is not just due to lack of nutrients, it can also be caused by enteric infections leading to intestinal inflammation and malabsorption of nutrients. Human genetic polymorphisms can alter host genes that affect nutrient absorption and metabolism. Changes in intestinal microbial ecology and the microbiome (the collective genome of the intestinal microbiota) can also affect the harvest of nutrients from the diet. A substantial proportion of malnourished children fail to recover due to inappropriate treatment. However, there may be other causes for treatment failure, including changes in the microbiome and infection with an enteropathogen, and a genetic predisposition to malnutrition may exist. It is, therefore, logical to undertake the following: 1) investigate genetic predisposition to malnutrition, 2) determine the genetic markers and biomarkers that can help identify children at risk of malnutrition, and 3) look for new treatment modalities that can improve the clinical management of children with malnutrition.

Socio-economic inequalities in childhood mortality in low- and middle-income countries: a review of the international evidence

INTRODUCTION

In low- and middle-income countries (LMICs), the probability of dying in childhood is strongly related to the socio-economic position of the parents or household in which the child is born. This article reviews the evidence on the magnitude of socio-economic inequalities in childhood mortality within LMICs, discusses possible causes and highlights entry points for intervention. Sources of data Evidence on socio-economic inequalities in childhood mortality in LMICs is mostly based on data from household surveys and demographic surveillance sites.

AREAS OF AGREEMENT

Childhood mortality is systematically and considerably higher among lower socio-economic groups within countries. Also most proximate mortality determinants, including malnutrition, exposure to infections, maternal characteristics and health care use show worse levels among more deprived groups. The magnitude of inequality varies between countries and over time, suggesting its amenability to intervention. Reducing inequalities in childhood mortality would substantially contribute to improving population health and reaching the Millennium Development Goals (MDGs).

AREAS OF CONTROVERSY

The contribution of specific determinants, including national policies, to childhood mortality inequalities remains uncertain. What works to reduce these inequalities, in particular whether policies should be universal or targeted to the poor, is much debated.

AREAS TIMELY FOR DEVELOPING RESEARCH

The increasing political attention for addressing health inequalities needs to be accompanied by more evidence on the contribution of specific determinants, and on ways to ensure that interventions reach lower socio-economic groups.

Enteropathogenic Escherichia coli inhibits intestinal vitamin B1 (thiamin) uptake: studies with human-derived intestinal epithelial Caco-2 cells

Infection with the gram-negative enteropathogenic Escherichia coli (EPEC), a food-borne pathogen, represents a significant risk to human health. Whereas diarrhea is a major consequence of this infection, malnutrition also occurs especially in severe and prolonged cases, which may aggravate the health status of the infected hosts. Here we examined the effect of EPEC infection on the intestinal uptake of the water-soluble vitamin B1 (thiamin) using an established human intestinal epithelial Caco-2 cell model. The results showed that infecting Caco-2 cells with wild-type EPEC (but not with nonpathogenic E. coli, killed EPEC, or filtered supernatant) leads to a significant (P < 0.01) inhibition in thiamin uptake. Kinetic parameters of both the nanomolar (mediated by THTR-2) and the micromolar (mediated by THTR-1) saturable thiamin uptake processes were affected by EPEC infection. Cell surface expression of hTHTR-1 and -2 proteins, (determined by the biotinylation method) showed a significantly (P < 0.01) lower expression in EPEC-treated cells compared with controls. EPEC infection also affected the steady-state mRNA levels as well as promoter activity of the SLC19A2 and SLC19A3 genes. Infecting Caco-2 cells with EPEC mutants that harbor mutations in the escN gene (which encodes a putative ATPase for the EPEC type III secretion system, TTSS) or the espA, espB, or espD genes (which encode structural components of the TTSS) did not affect thiamin uptake. On the other hand, mutations in espF and espH genes (which encode effector proteins) exhibited partial inhibition in thiamin uptake. These results demonstrate for the first time that EPEC infection of human intestinal epithelial cells leads to inhibition in thiamin uptake via effects on physiological and molecular parameters of hTHTR-1 and -2. Furthermore, the inhibition appears to be dependent on a functional TTSS of EPEC.

Effect of women's perceptions and household practices on children's waterborne illness in a low income community

An ecosystem approach to human health was adopted in a community-based study carried out in Bebnine, an underserved town in Lebanon. The objective of the study is to examine the association between women's household practices and diarrhea among children in a setting where contaminated drinking water and intestinal diseases are common. A total of 280 women were randomly selected and interviewed using a structured questionnaire. Data were collected on 712 children between the ages of 6 and 14. The study instrument included determinants of diarrhea such as sociodemographic characteristics, water, sanitation, hygiene practices, gender variables, and behavioral risk factors. Multivariate regression analysis was employed to examine the association between water handling practices and diarrhea. The prevalence of diarrhea is 5%. Female children are more likely to suffer from diarrhea than male children (OR = 2.58; 95% CI: 1.19-5.62). Treatment of drinking water at the household level and the use of drinking water for cooking and the preparation of hot beverages are protective against diarrhea (OR = 0.15; 95% CI: 0.03-0.65). Female caretakers' behaviors such as daily bathing and seeking medical care at times of illness are protective against diarrhea in children. The findings suggest that diarrhea is a gendered health problem. Female children, who are generally more involved in household activities than male children, are at higher risk of suffering from diarrhea. Female caretakers' personal hygiene, household practices, and perceptions of diarrhea are additional risk factors. Intervention activities would be more effective if based on a better understanding of gender roles and household power relations.

Attribution of malnutrition to cause-specific diarrheal illness: evidence from a prospective study of preschool children in Mirpur, Dhaka, Bangladesh

We examined whether malnutrition (underweight [WAZ] < -2) increased the risk of diarrhea equally for all enteropathogens. The study was conducted prospectively between January 1999 and July 2002 in Mirpur, an urban slum in Dhaka. Two hundred eighty-nine Bangladeshi children (147 male and 142 female) 2-5 years of age were included in the study. Malnutrition was present in 39% of the children at the time of enrollment. The parents and children were visited and interviewed every other day by health care workers for details about any diarrheal episodes. Stool samples were successfully collected from 62% of episodes of diarrhea. Of the identified enteropathogens, only enterotoxigenic Escherichia coli (ETEC), Cryptosporidium sp., and Entamoeba histolytica were significantly more prevalent in malnourished children. We concluded that the malnutrition attributed risk is not equal for enteric pathogens associated with diarrheal illness.

Targeting the human microbiome with antibiotics, probiotics, and prebiotics: gastroenterology enters the metagenomics era

Studies of metagenomics and the human microbiome will tremendously expand our knowledge of the composition of microbial communities in the human body. As our understanding of microbial variation and corresponding genetic parameters is refined, this information can be applied to rational remodeling or "tailoring" of human-associated microbial communities and their associated functions. Physiologic features such as the development of innate and adaptive immunity, relative susceptibilities to infections, immune tolerance, bioavailability of nutrients, and intestinal barrier function may be modified by changing the composition and functions of the microbial communities. The specialty of gastroenterology will be affected profoundly by the ability to modify the gastrointestinal microbiota through the rational deployment of antibiotics, probiotics, and prebiotics. Antibiotics might be used to remove or suppress undesirable components of the human microbiome. Probiotics can introduce missing microbial components with known beneficial functions for the human host. Prebiotics can enhance the proliferation of beneficial microbes or probiotics, to maximize sustainable changes in the human microbiome. Combinations of these approaches might provide synergistic and effective therapies for specific disorders. The human microbiome could be manipulated by such "smart" strategies to prevent and treat acute gastroenteritis, antibiotic-associated diarrhea and colitis, inflammatory bowel disease, irritable bowel syndrome, necrotizing enterocolitis, and a variety of other disorders.